Alcatel Carrier Internetworking Solutions 8800 User Manual

Troubleshooting ARP

ARP Protocol Failure

OmniSwitch Troubleshooting Guide

page 11-3

When device A ARPs for the gateway IP address exist on the switch, an associated ARP cache entry is 
created by the switch. This entry can be viewed by using the show arp command.

To search for a specific ARP entry, use the following command syntax:

show arp ip-address

For example:

-> show arp 10.255.11.219

Total 39 arp entries
Flags (P=Proxy, A=Authentication, V=VRRP)

 IP Addr           Hardware Addr       Type       Flags   Port     Interface
-----------------+-------------------+----------+-------+--------+-----------
10.10.42.159      08:00:20:a8:f0:8a DYNAMIC              16/ 2  vlan 10

To search for an ARP entry associated with a MAC address use the following command syntax:

show arp mac-address

For example:

-> show arp 10.255.11.219

Total 39 arp entries
Flags (P=Proxy, A=Authentication, V=VRRP)

 IP Addr           Hardware Addr       Type       Flags   Port     Interface
-----------------+-------------------+----------+-------+--------+-----------
10.10.42.159      08:00:20:a8:f0:8a DYNAMIC              16/ 2  vlan 10

This confirms that the switch has learned the ARP entry of the device A. 

Now, device A should have also resolved the ARP entry to the gateway IP address. It can be verified on 
the workstation’s command prompt using the following DoS command:

C:\> arp -a

Interface: 10.10.42.1 on Interface 0x1000003

  Internet Address      Physical Address      Type
  10.10.42.1             00-d0-95-79-62-d1     dynamic